Ideally I would expect the following calls and assertions to go together:

page['myid'].replace '<div>content</div>'

assert_select_rjs :replace, 'myid'

However this isn’t the case. Since you are using the page[id] syntax Rails considers this a “chained” selector so you have to use the following assertion:

assert_select_rjs :chained_replace, 'myid'

Ritarded, I know. So “ticket 8750”:http://dev.rubyonrails.org/ticket/8750 fixes this and you can now use the more intuitive syntax as demonstrated below:

page['myid'].replace '<div>content</div>'
assert_select_rjs :replace, 'myid'

page['myid'].replace_html '<div>content</div>'
assert_select_rjs :replace_html, 'myid'